_68_, _69_; Hartwell, 70; marine, 71. Speed of motor car, 105. Coal, as fuel, 15; gas, 394; gas plant, _396_; gas, purification of, 397. Cochlea, 273. Coherer, 140. Coil, Ruhmkorff, 121. Coke, 395. Combinations in Chubb lock, 436; Yale lock, 436. Combustion, 26, 393; perfect, 28. Compensating gear, 107, _108_. Gear-box of motor cars, 109. Siphon, _351_. Slide-valve, 49, 50, 51; setting of, 53. Sliders, 297. Sound, nature of, 270; board of piano, 283. Advancing the spark, 102. Air-gun, _342_. Air-pump for cycle tyres, _340_; for Westinghouse brake, 199. Alternating currents, 164; dynamo, 164. Amperage, 125. Angle of advance, 57, 58; incidence, 268; reflection.